“SoraBot-UVGI is a modular robot for sanitizing surfaces. It is small, it is equipped with self-driving, it is open-souce and low cost.
When I started this project, my first thought was that I had to make a robot buildable in a short time and at the lowest possible cost. I set myself the following main objectives:
Sanitation of environments and surfaces;
Low cost, for everyone;
Autonomous;
Configure the route in a simple way: path planning;
Set UVGI (Ultraviolet Germicidal Irradiation) points where you can stop and sanitize surfaces, such as handles, desks, chairs, sinks, toilets, etc…
Modular UVC lamps section.
First of all I gave it a name: SoraBot-UVGI.
I thought of making a robot that could be manufactured by as many people/companies as possible, so the cost of construction was a fundamental element. To keep the cost low I had to exclude all those sensors and components that would have made it rise. So, I immediately ruled out the use of cameras, Lidars, etc… and I thought of a solution based on a very low cost line sensor: a robot that would be able to follow a simple black (or white) tape drawn along the way. An optimized path along the perimeter of the surfaces to be sanitized would have allowed me to maximize the use of the battery and UVC lamps (the lamps have a certain number of operating hours and ignitions, beyond which they no longer work).
For the motors, I found a cheap kit solution: it costs only $62.5.
For the batteries, I used a 12V 7Ah lead acid battery in the tests, but more batteries could be inserted to increase the robot autonomy or it is also possible to use other types of batteries, such as LiPo.
In general, the number of batteries depends on the length of the path (read more in the Power Supply section) and how much surface needs to be sanitized (read more in the UVC Lamp Section).
I thought of using ROS (Robot Operating System) to control the robot. Linux Operating System is required. So I installed ROS on a Raspberry Pi 3, that is very cheap. Furthermore, ROS simplifies the expandability of the robot: for example, if another team wants to add a Lidar, they can do it and integrate it without changing the entire robot’s software and hardware.
I made SoraBot-UVGI autonomous: this way it could be used at any time and work even during closing hours, when there are no people. In any case, if there are people around, SoraBot-UVGI is equipped with two SS-430L-BK sensors that detect the presence of people through IRs. When one or more people enter the SoraBot-UVGI field of action, the robot stops, immediately turns off all UVC lamps and emits an audible alarm signal (beep beep beep).
Each company has a different building plan, that’s why I decided to create a line follower. With black tape on a light surface (or white on a dark surface), I created the path to follow inside the rooms and I marked with different colors the points to be sanitized (such as door handles). I equipped SoraBot-UVGI with two color sensors to identify these points. When the robot detects a line of a certain color (next to the black line), it performs additional operations: it can stop for some seconds or minutes, extend the UVC lamps to illuminate the surface of a table, while continuing the movement; it can approach a toilet and extend the lamps horizontally to sterilize its entire surface. I inserted two ultrasonic sensors (one at the front and one at the rear), so that, in the presence of obstacles, the robot stops (it is easy to implement a software system to circumvent any obstacles).”